title: Dominant negative mutant cyclin T1 proteins that inhibit HIV transcription by forming a kinase inactive complex with Tat.
abstract: Transcription of the human immunodeficiency virus type 1 (HIV) requires the interaction of the cyclin T1 (CycT1) subunit of a host cellular factor, the positive transcription elongation factor b (P-TEFb), with the viral Tat protein, at the transactivation response element (TAR) of nascent transcripts. Because of this virus-specific interaction, CycT1 may potentially serve as a target for the development of anti-HIV therapies. Here we report the development of a mutant CycT1 protein, containing three threonine-to-alanine substitutions in the linker region between two of the cyclin boxes, which displays a potent dominant negative effect on HIV transcription. Investigation into the inhibitory mechanism revealed that this mutant CycT1 interacted with Tat and the cyclin-dependent kinase 9 (Cdk9) subunit of P-TEFb, but failed to stimulate the Cdk9 kinase activity critical for elongation. This mutant CycT1 protein may represent a novel class of specific inhibitors of HIV transcription which could lead to development of new antiviral therapies.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4984, USA.
authors.forename: Julie K
authors.initials: JK
authors.lastname: Jadlowsky
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4984, USA.
authors.forename: Masanori
authors.initials: M
authors.lastname: Nojima
authors.affiliation: Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Okamoto
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4984, USA.
authors.forename: Koh
authors.initials: K
authors.lastname: Fujinaga
mesh_terms: D056906:Cyclin T; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism; D016213:Cyclins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006678:HIV / Q000235:genetics*; D006801:Humans; D008958:Models, Molecular; D020641:Polymorphism, Single Nucleotide; D011487:Protein Conformation; D021122:Protein Subunits / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000378:metabolism*
chemical_list: C503684:CCNT1 protein, human; D056906:Cyclin T; D016213:Cyclins; D021122:Protein Subunits; D054322:tat Gene Products, Human Immunodeficiency Virus; C467969:CDK9 protein, human; D042863:Cyclin-Dependent Kinase 9